设{an}是等差数列,bn={1/2}^an,已知b1+b2+b3=21/8,b1b2b3=1/8,证明{bn}是等比数列

如果数列{an}是等差数列,设bn=(1/2)^an,数列{bn}是等比数列吗? 设{an}是等差数列,an=2n-1,{bn}是等比数列,bn=2^(n-1)求｛an/bn｝前n项和Sn an+1^2-a^2=bn an是等差数列 求证bn是等差数列 一道求证等差数列题目,a1=1 ,an=2a(n-1)+ 2^(n-1) 设bn= an/2^(n-1) 求证bn是等差数列 求证等差数列,a1=1 ,an=2a(n-1)+ 2^(n-1) 设bn= an/2^(n-1) 求证bn是等差数列 如何证明：已知数列{an}是等差数列,设bn=2an+3a(n+1).求证：数列{bn}也是等差数列. 已知数列{an},{bn}满足a1=2,2an=1+2an*an+1,设{bn}=an-1求数列{1n}为等差数列急！！！ 设{an}是等差数列,bn=1/2^an,已知b1+b2+b3=21/8,b1*b2*b3=1/8,求等差数列的通项an? 设{an}是等差数列,bn=1/2^an,已知b1+b2+b3=21/8,b1*b2*b3=1/8,求等差数列的通项an? a1=1,an+1=2an+2^n 设bn=an/2^n-1 1证明bn是等差数列 2求an前n项和sna1=1,an+1=2an+2^n 设bn=an/2^n-1 1.证明bn是等差数列 2.求an前n项和sn 设数列{an}是等差数列,bn=(1/2)的an次方,又b1+b2+b3=21/8,b1b2b3=1/8,证明数列｛bn}是等比数列 设{an}是等差数列,bn={1/2}^an,已知b1+b2+b3=21/8,b1b2b3=1/8,证明{bn}是等比数列 数列{an}满足a1=1/2,an+1=1/2-an（n属于正整数）设bn=1/1-an,证明{bn}是等差数列,并求bn和an各位哥哥姐姐们谁会啊? 一道数学数列题设两个数列{An},{Bn}满足Bn=（A1+A2+A3+……+nAn)/(1+2+3+……+),若{Bn}为等差数列,求证{An}也是等差数列.那个，题目上是“若{Bn}为等差数列，求证{An}也是等差数列”要是“若{an}为等 在数列an中,a1=2,a2=4,an+1=3an-2an-1,设bn=log2(an+1-an)求证bn是等差数列,求数列1/bnbn+1的前n项和 设各项均为正数的数列{an}和{bn}满足:an,bn,an+1成等差数列,bn,an+1,bn+1等比数列且a1=1,b1=2,a2=3求通项an,bn 设各项均为正数的数列｛an}和｛bn}满足：an,bn,an+1成等差数列,bn,an+1,bn+1成等比数列,且a1=1,b1=2,a2=3,求通项an,bn 已知数列{an}是等差数列,且bn=an+a(n-1),求证bn也是等差数列